In the oil and gas industry, a common problem in drilling wells or boreholes in subterranean formations is the loss of circulation materials, such as fluids (for example, drilling fluids or muds), in a well or borehole during the drilling. Such lost fluids typically go into fractures induced by excessive mud pressures, into pre-existing open fractures, and/or into large openings with structural strength in the formation.
A large variety of materials have been used or proposed in attempts to cure lost circulation. Generally, such materials may be divided into five types or categories: fibrous materials, such as shredded automobile tires or sawdust; flaky materials, such as wood chips and mica flakes; granular materials, such as ground nutshells; slurries, whose strength increases with time after placement, such as hydraulic cement; and polymerizable compositions.
Polymerizable compositions comprise one or more monomer, typically, comprising optional components, such as for example fillers, which cure in situ downhole. Various polymerizable compositions are known and may comprise such polymerizable and/or polymeric materials as an epoxy resin, an organic siloxane, a phthalate resin, a (meth)acrylate resin, an isocyanate-based resin, a polyacrylamide, or the like. For examples see U.S. Pat. Nos. 3,181,611 and 7,696,133; and US Publication No. 2009/0221452 and 2010/0087566; and WO 2010/019535, each of which is incorporated by reference herein in their entirety.
Although many materials and compositions exist and have been proposed for preventing lost circulation, there continues to be a need for even more versatile and better compositions and methods for preventing loss of circulation.